Inescapable air pollution, which contributes to asthma, emphysema, heart disease, and other health conditions, poses a risk to people worldwide. Yet, good news can be found within all the smog: A study led by Duke University researchers finds air pollution controls enacted in North Carolina during the early 1990s coincide with decreasing death rates from emphysema, asthma, and pneumonia. “By following levels of air pollution and respiratory health over time, we could measure changes prior to and after implementation of these policies,” said Dr. H. Kim Lyerly, a professor of surgery, associate professor of pathology, and assistant professor of immunology at Duke. “Our study leverages these collected data in a way that it can contribute to the dialogue on whether pollution controls are effective in improving public health."

More than 20 years ago, national requirements lowered emissions from automotive engines, chemical plants, and coal-fired power plants, while targeting emissions that might contribute to acid rain and depletion of the ozone layer. More recently, in 2002, North Carolina passed the Clean Smokestacks Act, a state law that mandated significant reductions in emissions from coal-fired power plants. Together, both federal and state measures were designed to decrease airborne compounds considered to play a role in an estimated 1.4 percent of deaths worldwide. Considering the clean air regulations, a team of researchers wondered if, in fact, improved air quality might be linked to reduced rates of death from respiratory diseases in North Carolina?

Using mortality trends from state public health data, along with monthly measurements from air-monitoring stations across North Carolina between the years 1993 and 2010, the researchers analyzed the trends of emphysema, asthma, and pneumonia mortality against changes in the levels of ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, and two different types of particulate matters. Next, they controlled for factors such as lower smoking rates and month-to-month fluctuations in air quality. After sorting the numbers, the researchers calculated how each one-unit reduction in separate air pollution components coincided with a drop in deaths from emphysema, asthma and pneumonia.

Reductions of sulfur dioxide levels showed a significant correlation to lower death rates for emphysema, asthma and pneumonia, the researchers found. They also discovered decreases in carbon monoxide to be significantly associated with lower emphysema and asthma deaths, while reductions in fine particulates coincided with lower emphysema death rates and reductions in a second particulate matter were associated with lower asthma deaths.

“Significant associations were observed between decreasing death rates of emphysema, asthma, and pneumonia and decreases in levels of ambient air pollutants in North Carolina,” the authors wrote in the conclusion of their study. Just as health benefits are gained whenever smokers clean up their and give up cigarettes, it appears reducing the amount of general smog benefits the respiratory health of one and all.